topo maps gps and gis

The Earth and their Projection on MapsAerial Photos and rectified Ortho-PhotosTopographical Maps, Urban plansDegree (Lat/long), UTM-Grids on Topo-MapsUse of Handheld GPS Equipment (Garmin 72, Garmin 76 or Garmin Venture Etrex)Data Transfer to Office ComputerGIS-Reproduction and Appearance on digital Topo-Maps and Plans

Handle of GPS and GIS with Topo-and Orthophoto Maps a Practical Introduction

8/6/2008 - University Advisor Jan-Peter Mund (PhD Geographer) 2

Content of the training

1. Objectives and Timing of the training2. General Introduction to Topographical

Maps and Orthographical Photos3. Grids of the Earth4. Position and Measurements on maps5. Introduction to GPS Equipment6. Handling of Handheld GPS7. GPS - Data collection and storage8. GPS- Data Transfer to GIS (ArcView)


Schedule of the training (1)1. Afternoon: 13:00 to 16:302. Please be prepared to work in the field tomorrow

for some hours3. Please ask questions if you could not understand

what I am teaching or explaining ! - This is very important !

4. Please don’t be afraid to ask me questions !5. I have to express my deep thanks to RUA,

especially to H.E. our Rector who organized and supports this training together with the graduate school.

6. I wish us all a successful and fruitful training this week at RUA


Objectives of the training (1)1. Practical training on handling of

Global positioning system measurements (GPS)

2. Basic Information about Topographical Maps and Orthographical Photos

3. Transmission and teaching of general information about GPS

4. Opportunities and Facilities of handheld GPS5. Practical GPS measurements in the field in

relation to field survey tasks6. Transfer GPS-Data to Desktop-GIS (ArcView)


Topo- and Orthographic Maps - Intro (2)

1. What is a location in general ?2. What is a topographical map ?3. Which scales of Topo-Maps you know ?4. What you can find on a Topo-Map ?5. What is an Orthographical Photo6. Which scales of Orthophotos you know ?7. What you can see on Orthophotos ?8. How you can acquire Aerial Photos ?9. How you can produce Orthophotos ?10. What is an appropriate planning scale ?


What is a location in general ? (1)

Location only makes sense when the location is compared to some frame of reference. Relative location: Guesthouse Hy Hengly- # 67 E o2

right to the beauty salon

Absolute location:- 40 P 0492004; 1276629 (UTM)- N 11°32’54,6“ / E 104° 55‘’36,0“ (Lat Lon)


The relative location (1)Relative location:Guesthouse Hy Hengly- # 67 E o2 - right to the beauty salonWhy this is a relative location ?

Because this adress might exist in several cities in Cambodia. Their is a some uncertainty, still !


The absolute location (1)

Northpole

Greenwich, UKZero-Meridian

orPrime Meridian= 0°Longitude

Equator= 0° Latitude

Absolute location= W 92° 24‘’56.4“

Longitudeand North

34° 26’21.6“


What is a map in general ? (2)

A map is a graphic representation of selected geographic features represented on a plane surface

Maps are essentially models of the Earth’s surface

Maps always have limitations - they are never completely accurate, and they are always incomplete

Maps may misrepresent information or deceive the user (either deliberately or accidentally)


1. What is a topographical map?(2)

A Topographical map is…


2. Which scales of Topo-Maps you know ? (2)

Topographical maps in Cambodia are produced in following scales:

1. 1: old French Maps 1954

2. 1: old French Maps 1954

3. 1: new Min Transport 98 / 02

4. 1: new Min Transport 98 / 02

5. 1: Dep. of Geography

6. 1: Dep. of Geography


3. What you can find on a Topo-Map ? (2)

On Topographical maps you can find:1. B… A…. Str…2. R… L… Cha…3. R… T… Ra…4. I… L…5. L… O…6. Ma… Bui…7. Isoh…8. G… Geod.. P…


4. What is an Orthographical Photo ? (2)

An Orthographical Photo is a…


5. Which scales of Orthophotos you know ?(2)

Orthographical Photos are produced in following scales:

1. 1:

2. 1:

3. 1:

4. 1:

5. 1:


6. What you can see on Orthophotos ? (2)

On Orthographical Photos you can see the following objects:

1. R…

2. R…

3. Ra…

4. H… Bui…

5. L… Oc…

6. In… L…


7. How you can acquire Aerial Photos ? (2)

Aerial Photos (orthographic) can be acquired by using:

1. Metric Analogue cameras on small planes

2. Satellite borne digital camera

3. Pilot less small automatic planes

4. Small aerial balloons like hydrogen balloons


8. How you can produce Orthophotos ? (2)

Orthographical Photos can be produced using several techniques:


9. What is the appropriate planning scale ? (2)

The appropriate planning scale depend on the objective, the objects and the available scale of the base data.

That means, that you can not easily up- or down scale your data until it fits to the required scale.

Try to avoid down scaling of base data or maps, i.e. from 1: 25.000 to 1: 10.000.

You can up scale or generalize or your data as much as you like but with generalization you will loose information of the data.

An appropriate planning scale for urban environment is between 1: 1.000 to 1: 15.000.


Exact position measurementon Topo-Maps

Warming up Exercises with Topo-Maps

1. Bridge Nat. Road

2. AirportEntrance

3. Minorcrossroads

4. RailroadBridge


Warming up Exercises with Orthophotos

1. Major CrossroadsCentral Place

4. MinorBridge

Exact position measurementon Ortho-Photo

2. Minor Crossroads

3. NE–Cornerof building


The Earth is round? - Grids of the Earth (3)

Equatorial Diameter=12,758 km (7,927 mi.)

Polar Diameter=12,714 km (7,900 mi.)


Why do we need an ellipsoid?

European Remote Sensing satellite, ERS-1 from 780Km

This image depicts the earth’s shape without water and clouds. It looks like a sloppily peeled potato, not a smoothly shaped ellipsoid.

Calculation of geographic position on this irregular surface is very complex. Therefore a much simpler model is needed.This simplified mathematical surface is an

ellipsoid.


What is an ellipsoid

Semi-major Axis: a = 6371837 mSemi-minor Axis: b = 6356752.3142Flattening Ratio: f=(a-b)/a = 1/298.257223563

Rotate Ellipse in 3Dimensions:

a

b


Traditional Horizontal DatumsThe Traditional Approach

Many nations established their own regional datum.Used various national standards and procedures

Different time framesCalculated ellipsoids that fit well locally

Established initial point location and orientation with astronomic observations

Result: Inconsistent Datums


How to measure on a round Earth ? (3)

To measure a position on an approximately round object you can use only round parts of a circle that we call Arcs.The crossing of two arcs creates an exact position on the round earth, that is measurable in Degrees, Minutes and Seconds.


How to measure on a round Earth ? (3)

Measurement to know !

1 Degree Latitude ~111 km

1 Degree Longitude~111 km at Equator

and up to0 km at Poles= longitude convergence


What is a Grid ? (3)

A Grid is set of intersecting lines that allow position to be specified exactly at the crossings and also in-between the crossings


What is a Grid ? 2-Dimension (3)

Alphanumeric Grid


What is Cartesian Coordinate System (3)A three dimensional GRID Three dimensional right hand coordinate

system with an origin at the center of the earth and the X axis oriented at at the Prime Meridian and the Z at the North Pole

• X Axis Coordinate Distance from the Y-Z plane measured parallel to the X-Axis;positive from90º W Long to 90º E Long

• Y Axis Coordinate Perpendicular distancefrom the plane of the prime meridian; positive in the eastern hemisphere and negative in the western.

• Z Axis Coordinate Perpendicular distance from the plane of the equator; positive in the northern Hemispherenegative in the southern Hemisphere

X0º Long

Z

Y90°E

Prime Meridian

(X,Y,Z)

Equator


Geographic CoordinatesLatitude, Longitude, & Ellipsoidal HeightLatitude & Longitude are defined by the Prime

Meridian and the Equatorial reference planes

Geographic latitude Vertical angle fromthe equator to the normal of ellipsoid, positive in Northern Hemisphere andnegative in the southern

Geographic longitude Horizontal angle from the prime meridian positive in the eastern hemisphereand negative in the western

Geodetic height Distance normalfrom the reference ellipsoid

Observer’sMeridian

PrimeMeridian

Latitude

Longitude

Y

Z

XLat- lonN 11°32’54,6“E 104° 55‘’36,0“


Grids of the Earth (3) How to measure on an

approximately round body ?


Datum definition and location

A datum defines the initial point and reference

surface

A coordinate system determines how

locations are referenced from the

datum


NAD 27(Clarke Ellipsoid )

ED 50(International Ellipsoid)

Datum definition and locationLimitations to the different Datum Approach


Regional vs. Global Datum Approach

Global replaces regional datum with a common, accurate standardOne system for maps of the entire planet


WGS 84

North American DatumClarke 1866

South American DatumInternational Arc Datum

Clarke 1880

EuropeanDatum International WGS72 Datum

TokyoDatumBessel

Most widely used local Datum/Ellipsoid pairs

Indian 54 DatumIndian 60 Indian Thailand


Datum definition: Location in Cambodia

A coordinate system determines how

locations are referenced from the

datum

Definition of Indian 60 Grid Datum

Dx = 198Dy = 881Dz = 317dA = 861dF = 0,0000284


Rules of Thumb for Latitude Longitude

Rules of thumb for latitude• 1º Degree latitude ≅ 60 nautical miles (≅ 111km)

• 1’ Minute latitude ≅ 1 nautical mile (1853 m)

• 1” Second latitude ≅ 30 meters

• 0.1” 1/10 second latitude ≅ 3 meters

• 0.01” 1/100 second latitude ≅ 30 centimeters

Rules of thumb for longitude• Don’t forget longitude convergence

• Don’t forget the base 60 conversion

• 60 minutes per degree

• 60 seconds per minute


Grids of the Earth (3)

1. Lines of latitude are always parallel.

2. Lines of latitude are evenly-spaced.

3. Meridians of longitude converge at the Poles.

4. Meridians and parallels always cross at right angles.

Try to maintain these properties on paper.


… so, how to get it flat ? - Projections (3)

Map projections are used to transfer and project data from the round earth onto a flat peace of paper. There are several different kind of map projections.


Planar Projections (3)


Cylindrical Projections (3)


Projection Properties (3)

Shape: Maps that maintain true shape are called conformal (e.g. Mercator)

Like:UTMUniversTransversMercatorProjection


• Projecting the sphere onto a cylinder tangent to a central meridian.

• Distortion of scale, distance, direction and area increase away from the central meridian.

• If you rotate the cylinder every 6º of longitude you create the UTM projection.

• This projection is used on map scales of 1:500,000 and larger

UTM-Projection


Universal Tranverse MercatorThe UTM graticule coverage in belt No 1 -60

Each belt is 6O in longitude wide

1 30 60180o 180o0o

84o N

80o S

Equator 0 meters N10,000,000m N


Cylindrical Projections (3)UTM Projection and Coordinates:• Flat Grid extending from 84N to 80S• Each zone is numbered Eastward starting at 177°W (6°

wide from 180°W to 174°W)• Coordinates are read east then north• Many map products from foreign countries use UTMs


Universal Transverse Mercator Grid

2 3 4 5 6 7 8

2 3 4 5 6 7 8

2 3 4 5 6 7 8

2 3 4 5 6 7 8 2 3 4 5 6 7 8 16o

Zone 2 Zone 3 156o168o

174o

Central Meridian

2 3 4 5 6 7 8

Zone 4162o

00oo

1,700,0001,700,0001,600,0001,600,0001,500,0001,500,0001,400,0001,400,0001,300,0001,300,0001,200,0001,200,0001,100,0001,100,0001,000,0001,000,000900,000900,000

800,000800,000700,000700,000600,000600,000500,000500,000400,000400,000300,000300,000200,000200,000100,000100,000

0o


How many UTM Zones in total ?

Which Zone(s) for Cambodia ?

If we are on Position UTM ….0491150 1280495:

How far is the Central Meridiane of our Zone ?

In which Direction is the Central Meridian ?

UTM-Projection - Questions:


Projection Properties (3)ConformalShapes are maintained on the map as they are on the globe. Angles are preserved

Equal AreaMaps cannot simultaneously show shape and area accurately. Area of all features on the map have the same relative proportions and size as they do on the globe.

EquidistantScale stays the same across the entire map sheet.

So equal-area maps show only area accurately and conformal maps show only the shape accurately. Compromise Maps: Show neither area nor shape completely accurately


Warming up Exercises with maps

Please find Locations on the MapDetermine UTM Coordinates from theMap of the following points

on your Topographical Mapof Battam Bang City

as well as later

on your Orthographical Aerial Photo of Battam Bang City


Global Positioning System (GPS)

GarminEtrex VentureHandheld Outdoor 12 Band Reciever

Garmin GPS 72Handheld Personal Navigator 12 Band Reciever

Next lesson>Introduction to handle two different handheld GPS – ReceiverGarmin 72 and Garmin eTrex Venture

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